The present invention relates to fiber-reinforced pressure containers or vessels and is more particularly concerned with the design of such containers to avoid excess strains due to the effect of internal pressure.
It is known that the strain in the middle, cylindrical part of pressure vessel with domed ends is greater than on the ends in the sense that the cylindrical part would deformed into the form of a barrel if it were not strong enough. In order to take this into account, pressure vessels of fiber-reinforced material have been designed so that the cylindrical middle part is provided with a casing to increase the resistance to pressure of this part of the structure between the domed ends. Such a casing is generally in the form of wound-on tape or thread material that is impregnated with synthetic resin.
A further relevant design consideration is that the transitions between the middle part and the domed ends of such a pressure vessel are particularly likely to be damaged by excess strain. It is however so far not proved feasible to reinforce the transitions by winding on backup material as used on the middle part, since if the winding were to be extended beyond the cylindrical middle part onto the domed ends, the wound material would tend to slip off because of the rounded shape of the domes. For this reason it has so far not been possible to reduce the pressure-induced strain load at the transitions between the domed ends and the middle part of a pressure vessel of the sort in question without the use of such complex methods and apparatus which would mean that the production of such pressure containers would no longer be an economic proposition.